import requests
from lxml import etree

header = {
    "user-agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.54 Safari/537.36 Edg/95.0.1020.40"
}
url = "https://aabook.cc/book-3645.html"
content = requests.get(url=url, headers=header).text
tree = etree.HTML(content)
k=tree.xpath('//li[@class="xiaoshuomulu"]/a/@href')
print(k)